recur: Remove WIP recurrence overhaul implementation

The feature has been moved to 3.0 milestone. Also, we are now using
feature branches for development of new functionality, in order to make
the development branch more stable.

src/main.h

@@ -39,13 +39,13 @@
 
 // recur.cpp
 void handleRecurrence ();
+void handleUntil ();
 Datetime getNextRecurrence (Datetime&, std::string&);
 bool generateDueDates (Task&, std::vector <Datetime>&);
 void updateRecurrenceMask (Task&);
 
 // recur2.cpp
 void handleRecurrence2 ();
-void handleUntil ();
 
 // nag.cpp
 bool nag (Task&);